Development of Protected Change-Tracking (PCT) as an extension for
OpenDocument starts with determination of feasibility for implementation by
adaptation of existing ODF-based software.

There are two parts to the first stage:

Determination that PCT protected-change markers in ODF document
elements do not disrupt any non-PCT consumers, whether or not markers
are preserved. The markers will be seen as foreign attributes and
should be ignored.

Verification that the existing ODF 1.2 Package Document Signature
implementations can be adapted to the progressive signing of generations
of PCT-protected documents. That is, documents containing such
signed-changes progressions will be properly recognized as
verifiably-signed conventional ODF documents without disturbance by the
additional content carried for PCT. The verification of earlier
generations by rolling-back the material should also function using
existing ODF 1.2 Package Document Signature processing.

These are parallel activities since conventional consumers only see
markers if the base document of a PCT document-file is extracted and opened
by a down-level processor.

Achieving a proof-of-concept PCT-aware process involves some form of
modification to existing applications. That will introduce the next
stage of feasibility determination.